This invention relates to a primary film forming resin for nail lacquers and nail enamel formulations and more particularly is directed to a grafted polymeric film forming resin for nail polish which will function as a replacement for nitrocellulose.
Nail lacquers and enamels typically contain several ingredients among which are a primary film former, secondary film formers, plasticizers, solvents, colorants, and fillers. In the past, nitrocellulose has been the primary film former employed in the majority of nail polish formulations but it suffers from the disadvantages that it is explosive; it tends to discolor as a function of time rendering it aesthetically displeasing; and it is prone to undergo sharp changes in viscosity which make application difficult. Thus a need exists in the nail lacquer arts for an improved primary film forming material.
Unlike copolymers having a linear arrangement of sequences such as --AAABBB-- and --ABABAB--, graft copolymers are polymers in which the molecules are characterized by a main backbone chain to which side chains containing different atomic constituents are attached at various points along the main chain. For example a graft copolymer can be represented by the structure ##STR1## The monomer units A and B are referred to as the main chain or backbone, the sequence of C units is the side chain or graft, and X is the unit in the backbone to which the graft is attached.
Nail lacquers containing graft polymers are not new. U.S. Pat. No. 4,683,007 issued Jul. 28, 1987 discloses a nail polish which includes nitrocellulose grafted to vinyl and acrylic monomers for the purpose of increasing the settling resistance of nitrocellulose. The graft polymers of the present invention however differ from such nitrocellulose grafts in both the main chain units and side chain units employed. In contrast to the '007 patent, the nail lacquer primary film formers of this invention are copolymers in which the main chain includes acrylic ester monomer units and methacrylic ester monomer units, and wherein two differing side chains are grafted to the main chain including both carboxylic acid units and units of trialkoxysily functionality. While Examples 6, 7 and 10 of the '007 patent do not include nitrocellulose, the polymers formed therein contain backbones of all methacrylate units and contain no acrylate units as the polymers of the present invention. Further the polymers of the '007 patent do not include carboxyl units as grafted side chains and where they do include trialkoxysilyl units, the trialkoxysilyl units of the ' 007 patent are endblocking units rather than side chain grafts. Thus there is a significant difference between the materials of the present invention and the materials of the '007 patent.
Japanese Patent No. 2-25411 dated Jan. 26, 1990 relates to a durable coat cosmetic material including a nail enamel in which a dimethylpolysiloxane compound is copolymerized with acrylate and methacrylate monomers. However a linear polymer instead of a grafted polymer is obtained in which the backbone includes each of acrylate, methacrylate and trialkoxysilyl units. There are also no grafted side chains and no carboxyl unit grafted side chains in distinction to the materials of the present invention. As noted above the copolymeric film formers of the present invention are graft copolymers and not copolymers having linear arrangements of sequences only.